(a) Technical Field
The present invention generally relates to systems and devices for delivering coolant to an engine of a vehicle, such as electric-powered vehicles and hybrid vehicles (e.g., vehicles powered by an electric motor(s) and/or an internal combustion engine). More particularly, the present invention relates to an integrated pump, coolant flow control and heat exchange device and systems embodying same and yet more particularly, to such an integrated pump, flow control and heat exchange device having the ability to simultaneously control flow paths and flow volume.
(b) Background Art
Generally, a vehicle includes an engine, a transmission, a unit heater, a radiator, a pump for delivering coolant to the engine, and an engine control module. A typical cooling system used in a vehicle includes three main flow circuits: an engine bypass circuit, a circuit including a unit heater, and a circuit including a radiator.
Coolant flow may be controlled by a simple traditional wax pellet fixed temperature thermostat or a more complex coolant control valve with a drive motor, which has been developed as a replacement to the traditional wax pellet type thermostat. The coolant control valve changes coolant flow within the circuits based on a signal from a vehicle engine control module unit which is derived from engine coolant temperature.
The coolant control valve reduces engine warm up time by blocking coolant flow at initial cold start and also allowing the engine (coolant and oil) to operate at a higher temperature during normal driving to improve the engine lubricity by controlling the coolant temperature (and engine oil by default) within the engine at higher average temperatures.
The coolant control valve, however, does not provide a more rapid increase in the temperature of the transmission oil circuit because of the positional limitation of a transmission oil cooler. More specifically, the transmission oil cooler is typically located in a radiator end tank (i.e., oil to liquid (coolant) type heat exchanger), in the air stream (i.e., air to oil cooler) in front of the vehicle engine cooling module, or both in series depending on the transmission cooling demand requirements. Alternatively, it may be provided as a remotely mounted stand alone oil to coolant type cooler.
Such a transmission oil cooler is located within one of the three main flow circuits or an auxiliary circuit. Accordingly, as the coolant flows through the multiple coolant circuits, the transmission oil cooler is not fully utilizing the maximum cooling potential available for transmission oil cooling.
In the case where the transmission oil cooler is located in the front end area of the vehicle (either in the radiator tank or air stream), during cold weather driving, the transmission oil is typically cooled to the minimum operating temperature if allowed to flow within the heat exchangers provided for cooling. This causes the oil to warm up slowly and also can cause the oil to operate at a temperature which is lower than the temperature for optimum transmission oil lubricity. As a result, more transmission mechanical drag can be caused and vehicle fuel economy during cold weather conditions can be reduced. In case of the air to oil transmission oil cooler, if there is no temperature bypass valve in the flow circuit, the oil in the cooler can get so cold and thick that the oil cooler may freeze and may not ever allow oil to pass through the cooler. In some cases, this may cause the transmission to be overheated and be damaged due to no oil flow through the transmission oil cooler.
An additional parasitic loss to the engine fuel economy performance is the engine driven mechanical water pump. The engine driven mechanical water pump always operates at some multiple or fraction of engine speed regardless of ambient temperatures or actual cooling requirements. Some vehicles have recently introduced an electric water pump on an internal combustion engine but this design traditionally has been avoided due to vehicle electrical power limitations because of the high current draw required to support a stand alone water pump capable of flowing enough coolant to properly cool the vehicle. As is known to those skilled in the art, such a engine driven mechanical water pump or front end assembly drive (FEAD) mechanically driven impellor/pulley water pump is driven by the engine so as to rotate at a multiple of the crankshaft rotational speed. Typically, the pump pulley is operably coupled to the crankshaft by a belt (e.g., serpentine belt).
Although devices and systems were proposed to increase the speed of transmission oil warm up, as disclosed in, for example, U.S. Pat. Nos. 6,182,749; 6,371,060; 6,997,143; 6,705,586; 6,796,375; 7,077,776 and 7,168,397, there is still a need for an improved device or system.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.